User's Manual
Table Of Contents
- Contents
- Figures
- Tables
- Document History
- Introduction
- Product concept
- Application Interface
- Antenna interface
- Electrical, reliability and radio characteristics
- Mechanics
- Reference Approval
- List of parts and accessories
MC46 Hardware Interface Description
DRAFT
MC46_HD_V02.8xb Page 35 of 98 21.08.2003
3.3.3.4 Undervoltage shutdown if no battery NTC is present
The undervoltage protection is also effective in applications, where no NTC connects to the
BATT_TEMP terminal. Thus, you can take advantage of this feature even though the
application handles the charging process or MC46 is fed by a fixed supply voltage. All you
need to do is executing the write command AT^SBC=<current> which automatically enables
the presentation of URCs. You do not need to specify <current>.
Whenever the supply voltage falls below the specified value (see Table 28) the URC
^SBC: Undervoltage
appears several times before the module switches off.
3.3.3.5 Overvoltage shutdown
If the supply voltage raises to V
BATT+
>5.8V, or an unrecoverable hardware or software error
occurs, the PSU-ASIC immediately cuts off the power supply to all components it is
connected to. In contrast to undervoltage shutdown, loss of data cannot be avoided.
Furthermore, there is no URC function available for overvoltage conditions, i.e. no alert will
be sent prior to shutdown.
Keep in mind that several MC46 components are directly linked to BATT+ and, therefore,
power remains applied at major parts of MC46. Particular attention must be paid to the
power amplifier which is very sensitive to high voltage and might even be destroyed.
Generally, to avoid that the MC46 application violates GSM specifications, be sure that the
supply voltage does not exceed the maximum value of 4.5V stated in Table 28.
3.4 Automatic GPRS Multislot Class change
XC18 features an integrated temperature control for GPRS multislot operation. If the board
temperature increases to the limit specified for restricted operation
1)
while data are
transmitted over GPRS, it is likely that the module automatically reverts to a lower GPRS
Multislot Class, for example from Class 10 (2 Tx) to Class 8 (1Tx). This reduces the current
consumption and, consequently, causes the board’s temperature to decrease. Once the
temperature drops to a value of 5 degrees below the limit of restricted operation, XC18
returns to the higher Multislot Class. If the temperature stays at the critical level or even
continues to rise, XC18 will not switch back to the higher class.
If the temperature rises and drops in a rapid succession within less than a minute, the
transition from one Multislot Class to another takes at least one minute.
Please note that there is not one single cause of switching over to a lower GPRS Multislot
Class. Rather it is the result of an interaction of several factors, such as the board
temperature that depends largely on the ambient temperature, the operating mode and the
transmit power.
1)
See Table 26 for temperature limits known as restricted operation.